Older Bolder Life

Stronger | Leaner | Sharper | Longer - From Older Bolder Fitness

aerobic fitness

Quick Monday Read: Low Ketone Readings while in Nutritional Ketosis

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Over the weekend a couple of questions popped up from two former clients who have both successfully been enjoying a ketogenic diet for several months now – the questions had to do with seeing progressively lower ketone readings on their surveillance testing (one serum, one breath).

In the midst of an all hands on deck family issue this weekend limiting my ability to expand in detail today, somewhat fortuitously Mark Sisson’s team, over on Mark’s Daily Apple, had reposted an article addressing the issue they’d written several years back – Why Am I Getting Low Ketone Readings on a Ketogenic Diet?

Sisson’s team covered most of the bases quite adequately, and in most cases where this question arises, from where I sit these days, most often what we’re seeing ketone/fat adaptation and/or the free fatty acid adaptation initially described by Volek and Phinney. And the discussion of whether or not physicians may or may not understand the keto phenomenon in the comments is fairly entertaining as well.

Most importantly, it’s imperative to look at the big picture – how does one feel and perform in day to day function and during workouts, are you where you want to be with regard to body composition, are you still dropping body fat if that’s your intent, are you symptomatic at all with anything resembling the “keto flu”, and how are you performing in aerobic level (vs anaerobic) exercise and activities?

Successfully implementing a nutritional ketosis program has very little is anything to do with readings on your serum or breath analyzer at home, don’t fall for anyone telling you otherwise.

Useful Gear: Tracking Heart Rates

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Today’s post is somewhat of a follow-up to a Question of the Day post back on 4 June about target heart rates; I talked back then about the critical differences between thinking about target maximal heart rates and target aerobic training heart rates.

By the way, if you’re not as familiar with the concept of target aerobic training heart rates, spend a bit of time reading Dr. Phil Maffetone’s work on the topic – here’s a great introduction to the topic on his site. (I still think his 180 formula is sheer genius and a great starting place for just about any and everyone considering an aerobic training program.)

There are a host of great wearable trackers out there – that’s my own Suunto Fitness 3 from a recent walk above – including those from Garmin, Fitbit, and Suunto for example, as well as many of the big-tech watches/wearable devices (like an Apple watch).

As I’ve progressed in my own fitness, I’ve found the heart rate tracking feature particularly helpful to make sure I’m getting into my aerobic training zone during my get-the-day-started early walks, and later when doing my (more often than not) twice-weekly sprint workouts tracking heart rate recovery for pacing all-out sprint efforts.

Tangentially, on the advice of a mentor in the health, wellness, and fitness game, my wife and I have even been tracking the impacts of different foods on sleep quality and nighttime heart rates (here’s looking at you, dark chocolate squares after dinner) – some consistent and reproducible patterns appear to be evolving. I’ll be sharing more down the road…

At least from where I sit, for most of us, choosing a specific device isn’t the critical issue; your budget in fact, and your interest (and/or ability) to take a deep dive into a new tech device (some of which are impressively complicated), may be the more critical limiting factor.

Clearly some of us in the ancestral health and fitness world tend to be a bit compulsive about data tracking and can lose sight of the big picture behind the avalanche of data before us; take care to not venture too far on the data analytics limb.

A useful rule of thumb I offer clients, and used to offer patients is this: never pursue testing or data tracking unless you expect the findings to have a genuine impact on how your manage your day, diet, training, etc.

Tracking your training heart rate will have a meaningful impact on how you approach your fitness, and is a great place to start if you’ve not been harvesting any training related data at all.

Sprinting: A Definitive and Easy Read

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Mark Sisson and his team over on Mark’s Daily Apple have recently posted a nifty two-part series on sprinting, something just about all of us should be doing in one form or another. Read Part One here and then Part Two here (includes a short video of Mark sprinting on the beach).

I was a competitive sprinter in my youth, and sprinted in the context of other sports in college and grad school (even playing the occasional flag football and Ultimate match in later years), though as my weight blossomed sprinting became a distant memory for over two decades.

Several years ago when beginning my own health reclamation I knew that I needed to add some form of sprinting back into the mix, though when I first starting my journey back, weighing over 400 pounds made that almost impossible. I eventually added hill sprints and cycling sprints into the mix, but have been enjoying the heck out of all out running sprints on a well-maintained soccer/football field most of all for the past several months.

There is something about running at (more or less) all-out effort that feels incredibly invigorating and plain youthful (something this 60 year old hasn’t necessarily felt in a while). As I’ve shared before, I do my main workouts every day fasted, my weekly sprints included, and I’ll swear my energy levels are even better on sprint days (and for a few days thereafter). More on sprinting, including some interesting research data, to come.

Question of the Day 4 June: Target Heart Rates

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From Cyndie in Kentucky this week –

…A friend working with a trainer has been telling me that walking isn’t enough of a workout to help me drop some weight. Her trainer says that you have to get your heart rate up really high to make fat burn, and told her to take my age (42) from 220 to get my target heart rate. That sounds really high and is hard for me to do walking, this doesn’t sound right to me…

Cyndie, appreciate the opportunity today to answer your question, and you’re right, the information passed on from your friend’s trainer is actually not correct.

The rule of thumb the trainer appears to have suggested you use, the 220 – your age calculation, is a commonly used rule of thumb (for example, used here by the Mayo Clinic) to estimate an individual’s Maximum Heart Rate target. There are of course potential flaws in using a rule of thumb calculation here, as there are of course other issue that may modify the results, such as medications you’re taking (i.e. beta blockers), your overall health, your overall fitness level, your fitness history (how long have you been working out and what types of exercise have you done), your injury history, and more.

Using the rule of thumb above, your target maximal heart rate would be 178. But that’s not really the number you need to be thinking about…

You Really Want to Your Use Your Heart Rate Guides to Work Aerobically to Burn Fat

When you go through your day completing most of your routine tasks (clinically called activities of daily living), you’re not exercising anywhere near your maximal heart rate; your body is working aerobically to burn fuels efficiently using oxygen. In the right setting metabolically, that includes burning fat as fuel, which from your question is what you’re trying to do.

If you significantly up the intensity of your effort (exercise or really aggressive ADLs), there is a point at which your body is forced to change over to another fuel processing system – anaerobic work – think of this like the maximal effort you might make when doing repetitive sprints as part of a training program. That’s stressful, inducing the production of stress hormones (which among other things slows down fat burning), and can lead to overtraining, excessive inflammation, and injury.

So you really want to know your maximal aerobic training heart rate.

Thankfully, a host of smart men and women have done the hard work and derived some fairly easy calculations to discover that number. My favorite is Dr. Maffetone’s 180 Formula.

Simply put, you subtract your age from 180, and modify that number using the four criteria he’s listed at the link above. From what you’ve shared, it appears your calculations would be 180 – 42 = 138, with another 5 subtracted as you’re just getting back into training (Dr. Maffetone’s modifier [b]), making your maximal aerobic training target a heart rate of 133.

Note that’s the maximal suggested target rate, and brisk walking, or walking hills should readily get you in the range of 85% to 90% of your maximal aerobic target, and will very likely aid in burning fat, which you’ve stated is your primary goal.

These numbers are of course rule of thumb guidelines, and must be modified specifically to match your own unique and specific health and fitness. Keep up the good work and get out there walking – I’m a huuuuuge fan of walking as a fitness and weight loss tool.